Machine for hobbing and shaving gearwheels



June15, 1965 F. HURTH mcrmm FOR 1103mm AND SHAVING GEARWHEELS 5 Sheets-Sheet 1 Filed June 4, 1962 IN VEN 7' 0K June 15, 1965 F. HURTH 3,188,915

' MACHINE FOR HOBBING AND SHAVING GEARWHEELS Filed June 4, 1962 5 Sheets-Sheet 3 X II/4W wlllllllllllllllg flllll'llllllll llllllllllllana &

June 15, 1965 F. HURTH 3,188,915

MACHINE FOR HOBBING AND SHAVING GEARWHEELS Filed June 4, 1962 5 Sheets-Sheet 4 'l/IIIIII;

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June 15 F965 F. HURTH 3,188,915

MA'QH'INE FQR HQBBING AND SHAVING' GEARWHEELS milled! June 4'. 1962 5 Sheets-Sheet 5 All/[Ma]? United States Patent 6 Claims. (a. sit-1.6

The invention relates to a method of and a machine for shaving gearwheels on a gearwheel hob with a shaving head supporting a shaving wheel or the like, said shaving head being interchangeable with a hobbing head disposed on a tool carriage which is adapted to be slidable and guided on a strand.

On combined machines for the coarse and fine finishing of gearwheels, for example on combined hobbing and shaving machines, it was possible hitherto only to produce gear wheels with cylindrical hobbing elements (pitch cylinder), i.e. with teeth exhibiting to longitudinal convexity. It is known that gear-wheels are fundamentally provided with convex teeth so that so-called edge-supports, which are caused by inaccurate seating, faults in tooth direction, shaft curvature or other divergencies from the desired geometric conditions, can be avoided. It is unjustified, though, to provide for such deficiencies in small or medium-sized gearwheels but not in large I gearwheels.

It is further conceivable to transfer one of the known convex shaving devices from the small gearwheel shaving machine, to the large shaving machine, but this, in relation to the combined hobbing and shaving machine, has

so far proved to be fraught with such difficulties as to induce operators entirely to dispense with convex shaved large gearwheels.

According to the invention, it is intended to avoid this defect in combined hobbing and shaving machines by a shaving method which is carried out in a manner such that the shaving gear wheel, at the start of the shaving feed motion, is inclined towards the plane of the tool carriage guide in such a Way that a radius vector of the shaving wheel forms with this plane an acute angle a and so that, upon further feeding towards the middle of the gearwheel, the shaving wheel assumes an upright position so that a radius vector of the shaving wheel approximately in the region of the wheel centre is perpendicular to the said plane, the shaving wheel being then oppositely inclined to the plane at the other end of the gearwheel being machined, to form an acute angle ct.

Already known is a combined gearwheel hobbing and shaving machine in which a tool carriage, displaceable with a milling feed, is disposed on a stand and carries, as desired, a hobbing head or shaving head, separate guiding and feeding means being provided for the bobbing feed or shaving feed. This machine is particularly adapted for use as a basis for carrying out the method according to the invention. It is then so constructed that the plane of the guide for the shaving feed can be titled in respect of the plane of the guide for the hobbing feed (German Patent No. 1,010,803).

In the machine described, the hobbing head and shaving head are mounted on the same tool carriage. To carry out the method, however, this is not a compulsory feature, it being possible to mount only the bobbing head on the tool carriage, providing for the shaving head a separate carriage displaceable on the guide for the tool carriage.

To produce longitudinally convex teeth, the machine for carrying out the method is so designed that the plane of the guide for the shaving feed may be continuously tilted at a pro-selectable cadence and preferably as a function of the shaving feed.

The machines for shaving large gearwheels differs from that for small gearwheels in that the workpiece drives the tool. Since the large workpiece is of correspondingly large size, the shaving head must be suspended in a manner adapted to these more difficult conditions. If the shaving head is then provided with a device for convex shaving, then this naturally reduces the rigidity of the shaving head mounting, or the device for convex shaving must be devised to ensure that it is strong enough to satisfy the higher demands made on it, which calls for greater expenditure. Surprisingly, then, it has become manifest that it is not at all absolutely essential, in order to avoid edge supports, to have the teeth shaved convexly in known manner, but that it is sufi'icient to shape them somewhat conically on both sides in order to achieve the same eifect. This knowledge is of the utmost importance with regard to large shaving machines, and, in particular, large combined machines.

Such a design of machine is now possible, namely, in that the plane of the guide for the shaving feed is adjustable and lockable in its inclination to the plane of the aide for the hobbing feed. This has the advantage that, firstiy, no controlling means for the convex shaving is required and that, secondly, the mounting can be far more rigidly devised and that, above all, the shaving head-quite apart from the feeding means-can be completely fixedly adjusted. It is true that this embodiment of the invention apparently has the disadvantage that the gearwheel cannot be continuously shaved. However, in practice, this disadvantage is without significance, because the machining of large gearwheels takes such a long time that the time spent on rearrangement is insignificant when compared with the investment outlay on the expensive apparatus. Above all, there is the advantage of great rigidity, which ensures minimal gear errors.

The last-described apparatus also facilitates the adjustment of the shaving device to permit production of accurately cylindrical gearwheels independently of an otherwise not entirely accurate running machine.

The invention is illustrated in the accompanying drawings, comprising FIGURES l to 10 wherein:

FIG. 1 shows a combined gearwheel hobbing and shaving machine;

FIG. 2 is the machine in FIG. 1 but viewed from a different direction, fitted with a hobbing head;

FIG. 3 is the machine in FIG. I, viewed as in FIG. 2 but fitted with a shaving head;

FIG. 4 is a simplified representation of the method according to the invention;

FIG. 5 is a longitudinal section through the tool carriage with shaving head fitted;

FIG. 6 is a section along the line 6-6, FIG. 5;

FIG. 7 is a section along the line 77, FIG. 5;

FIG. 8 is a longitudinal section through a diiierently constructed shaving head;

FIG. 9 is a section along the line 99, FIG. 8; and

FIG. 10 is a tooth of a gearwheel which has been comically shaved on both sides (in exaggerated representa tion).

FIG. 1 shows a hobbing machine of known design, in which a gearwheel 13 which is to be machined is mounted on a circular table 11 by means of a clamping device 12. The circular table 11 is mounted on the base 14 of the machine, on which a column or upright support is disposed so as to be displaceable radially to the workpiece 13. Disposed on the column 15 so as to be displaceable in a guide 16 running parallel to the axis of the workpiece is a tool carriage 17 which is moved by a feed spindle 18 which simultaneously provides the hobbing feed. A hobbing head 19 or shaving head 20, as desired, can be mounted on the tool carriage. On the shaving head 20 is a shaving carriage 21 which is longitudinally displaceable on a separate guide 22. To provide the feed of the shaving carriage, a special shaving feed spindle feed path, form with the plane 26 an angle diverging from 7 90 bya greater or less extent, as required. The convex- 23 is provided. The circular table can 'be driven at various speeds according to the hobbing or shaving. The

hobbing head is adjustable to suit the spiral angleof the workpiece and thespiral angleof the hob. The shaving head can be adjusted according to a desired shaving feed" direction and the, shaving tool itselfaccording to the spiral angles of workpiece and tool, so that shaving along crossing axes is possible. With the known machine so far described it is only possible to machine cylindrical, gear}, wheels (with pitch cylinder). 7

In order to remedy the defectslisted at the outset, the shaving gearwheel is now, according to the invention, not so guided that, as previously, one of its radius vectors 25 is always at right angles to the plane 25 of the,

guide 16.for the bobbing. feed, but. the tool is so'guided that, at commencement of shaving, a radius vector 2541' of the shaving gearwheel forms an obtuse angle withthe aforesaid plane 26, so 'that, during the course of the machining operation, the shaving wheel straightens up'so that a radius vector 25 is atri'ght-angles to the plane over shaving tilting arrangement can be rendered inoperative by means of one ora plurality of locking screws 44, of which one or more may be disposed on the side of the pedestal bearing 30.

The tilting arrangement shown in FIG. 5, with the eccentricbushes, is only to beconsidered as a diagrammatic representation. Other control arrangements can also'be employed. ,Among the form-locking controls,

. 'for example, mention should be made of the link motion devices with theirva riantsr The coulisse or link is inclined at a greater or lesser angle to the plane 26 and is sensed by, a feeling member attached to the shaving carriage 21. ln this case,-itis possible to dispense with theeccentric bushes and'suspend the guide plate in the a pre-selectable length of the gearwheel and that, finally, j

the shaving wheel assumes an opposite inclination to the plane, so that a radius vector b, upon completion of" the machining operation, forms an acute angle u'v/ith T a 'mechanical or hydraulic, resilient; force;

the plane, said angle being equal or unequal to the angle a. In this manner, 'a.convexly shaven gearwheel 13, as shown in FIG. 4; is produced. 7 V

FIGS. 5 to 7 show in diagrammatic representation an apparatus for carrying out this methodf Qn" the .tool

carriage 17 which is provided witha feed nut 17a (shown in diagrammatic representation only) for the feed spindle 18, is a base plate 2'7 which is swivellable about a centerv .ing pivot 28 is adapted to be locked by means .of a screw (not shown); The base plate is provided with two pedestal bearings shown in FIG. 9. The tilting arrangement can also be posittively controlled. I Then, too, theeccentric mounting members 31 and33 can be replacedby a single spindle. The eccentric members 32 and 34 are replaced by a rotatable or displaceable cam against which the guide plate is pressed by The cam is then, like the eccentric bush '34, controlled according to a predetermined programme.

With theapparatus describedthus far, the method ac 29Wl'tl1 a single spindle somewhat as cording to the invention iscarried out with a continuous control; That is not necessary. Particularly Where large machines are concerned; the apparatus nowtobe described, with reference to FIGS. 8 tojlO, offersparticular advantages. 7 V

(The guide plate'35 is mounted on. the base plate 27. in

they pedestal bearings '29, with only one, single spindle 45.

pedestal bearings 29 and 30 in which, by. meansof respec-f tive spindles 31 and 32 and respective eccentric bushes 33 and'34, a guide plate is mounted. Said guide 7 is provided with the already mentioned longitudinal guide 22 for the shaving carriage 21. On the shaving carriage 21 is the tool support 36, which is adapted to be swivellable plate f about a centering pivot 37-, and to be locked by means of a screw (not shown). In the tool support, the shaving wheel 24 is mounted on a working spindle 39, through the medium of an eccentric bush 40. By means of the V,

eccentric bush, theshaving wheelcan, when handwheel 41 is turned, be brought closer to or removed farther from theworkpiece, for feed purposes,, whi ch, is illus -trated in FIG. 9, no further explanation being necessary.

The shaving carriage 21 is moved by a shaving spindle 23 which can be driven by a motor through a wormdrive 42 and a change-over gear (not shown). Whereas the spindle 31 and eccentric bush33 are mounted tobefreely rotatable, in a virtually clearance-free manner (anti-tric- H tion bearings may even be used), the eccentric bushfld,

as shown in FIG. 6, is provided with'a controlling mem-.

The eccentric control of the embodiment shown in FIG. 5. is replaced'by a wedgeeshaped member '46 which can be adjusted'in known manner by: means of an adjuster screw 47. By adjustment-of the wedge-shaped member of the plane of the guide 22 for feed of the shaving carwheelswliichapproximate these very closely can indeed be produced, --FIG. .10 shows an exaggerated diagram of such a tooth. Initially, the guide plate 35 can be so inclined that one end 550 of the tooth is shaved to a greater or lesser conical configuration, then again, the guide plate can be adjusted parallel to the-guide 16, in order to shave the middle portion.51 of the tooth cylindrically ber 34a, for example a gear or wor'm wheel segment so that it may sothat it' may be driven by a mechanical, hydraulic or electric positioning-motor'(not-shown). for example through a worm 43. 7 By turningthe' eccentric bush 34, the guide platev 35 v or lesser degree, the movementcornponent in the direction of feed being allowed for by the eccentric bush 33;

The positioning motor for the eccentric bush 34' can be controlled according to 'a predetermined plan, for example, by 'a cam plate, in relation to "the feed or rate of advance of the shaving carriage'21, or feedfor'rate of advance of the tool carriage 17-; The control plan of the positioning motor can,'however, also be derived from: any other factors. By means ofthis positioning motor and the eccentric bush .34, the guide plat-ejcan now be s'wivelled during the advance of the shaving carriage I that a radius vector of the shavinggearwheel 24 can,

over a predetermined time, i.e. during a' predetermined can be tilted to a greater and, finally, the; guideplate is tilted towards the other side for conical'shaving of the othervend 52 of the gear wheel. It goes without sayingthat deparature from this sequence of operations is possible. The eifect oi? such a gearwheel 'very closely approximates that of a convexly shaven wheel. 'Theapparatus for producing such 1. A device for shaving large gears in a gear bobbing a wheel is distinctiveby' virtue of simplicity and above all, since the-tilting deviee'can' be locked, by greater rigidity; .Adjustment of the-angle of inclination is likewise very simple if-a'gauge 54 or-tthe like'is disposed on the shavingcarriage'and'is adapted to scan a measuring surface 55 parallel to the plane'26 (FIG. 9).

. I claim? and millingimachine having asupport and a milling car- 'riage guided thereon in a first plane and comprising; a

shaving'headhaving'a'base detachably mounted on said carriage, a member having planar guide means thereon,

means tiltably mounting said member on said base, shaving tool means displaceable along said guide means, means for tilting said member on said base to vary the angle between said guiding means and said first plane, and means for locking said member in its tilted positions on said base.

2. A device for shaving large gears in a gear hobbing and milling machine having a support and a milling carriage guided thereon in a first plane and comprising; a shaving head having a base detachably mounted on said carriage, means pivotally mounting a member on said base, said member having planar guide means, shaving tool means mounted on the said guide means of said member, drive means for driving the shaving tool means along said guide means, power operated means for tilting said member about its pivotal connection with said base, and means for locking said member in its tilted positions on said base, said means pivotally mounting said member on said base comprising a shaft and eccentric bushing means surrounding said shaft.

3. A device for shaving large gears in a gear hobbing and milling machine having a support and a milling carriage guided thereon in a first plane and comprising; a shaving head having a base detachably mounted on said carriage, means pivotally mounting a member on said base, said member having planar guide means, shaving tool means mounted on said member, drive means for driving the shaving tool means along said guide means, and power operated self-locking drive means for tilting said member about its pivotal connection with said base.

4. A device for shaving large gears in a gear hobbing and milling machine having a support and a milling carriage guided thereon in a first plane and comprising; a

shaving head having a base detachably mounted on said carriage, means pivotally mounting a member on said base, said member having planar guide means, shaving tool means mounted on said member, drive means for driving the shaving tool means along said guide means, and means for locking said member to said base in adjusted positions thereon.

5. A device for shaving large gears in a gear hobbing and milling machine having a support and a milling carriage guided thereon in a first plane and comprising; a shaving head having a base detachably mounted on said carriage, means pivotally mounting a member on said base, said member having planar guide means, shaving tool means mounted on said member, drive means for driving the shaving tool means along said guide means, power operated means operable for reversibly tilting said member on said base during movement of said milling carriage in one direction, and means for locking said member in its tilted positions on said base.

6. A device for shaving large gears in a gear hobbing and milling machine having a support and a milling carriage guided thereon in a first plane and comprising; a shaving head having a base detachably mounted on said carriage, means pivotally mounting a member on said base, said member having planar guide means, shaving tool means mounted on said member, drive means for driving the shaving tool means along said guide means, power operated means operable for reversibly tilting said member on said base during movement of said milling carriage in one direction, said shaving tool means including a base element and a tool carrier swivelly mounted thereon, and means for locking said member in its tilted positions on said base.

References Cited by the Examiner UNITED STATES PATENTS 2,346,266 4/44 Mentley 901.6 2,536,343 1/51 Austin 901.6 2,542,569 2/51 Praeg 901.6 2,547,517 4/51 Austin 90-1.6 2,762,268 9/ 56 Maurer 901.6 2,882,799 4/59 Budnick 90-1.6 2,953,067 9/60 Ufert 901.6

FOREIGN PATENTS 1,260,297 3/61 France. 1,117,360 4/ 60 Germany.

ANDREW R. JUHASZ, Primary Examiner. LEON PEAR, Examiner. 

1. A DEVICE FOR SHAVING LARGE GEARS IN A GEAR HOBBING AND MILLING MACHINE HAVING A SUPPORT AND A MILLING CARRIAGE GUIDED THEREON IN A FIRST PLANE AND COMPRISING; A SHAVING HEAD HAVING A BASE DETACHABLY MOUNTED ON SAID CARRIAGE, A MEMBER HAVING PLANAR GUIDE MEANS THEREON, MEANS TILTABLY MOUNTING SAID MEMBER ON SAID BASE, SHAVING TOOL MEANS DISPLACEABLE ALONG SAID GUIDE MEANS, MEANS FOR TILTING SAID MEMBER ON SAID BASE TO VARY THE ANGLE BETWEEN SAID GUIDING MEANS AND SAID FIRST PLANE, AND MEANS FOR LOCKING SAID MEMBER IN ITS TILTED POSITIONS ON SAID BASE. 